Soil Sampling & Testing: a quick-and-dirty look

By knoxred (knoxred) on September 13, 2010

So the lawn is looking sad and you're thinking about renovating it this fall. What is the first thing you should buy?
(Hint: It's not grass seed.)

The best investment you can make in your lawn is actually very inexpensive, and fall is the very best time to do it.  Spend a few bucks on a professional soil test to pinpoint exactly what your soil needs to support your chosen grass type.  Contact your County Extension office to find out what their procedures are, and to get an official sample container or bag.  Here's a link to help you find the nearest Extension office.

Follow your particular Extension's instructions, but the general idea is this:

1) Take core samples from your target area, in this case your lawn.  2010-09-06/knoxred/8d9b8aA soil sampler is excellent for this purpose, but if that's not in your toolbox, a plain old trowel or shovel will do nicely.  Take "slices" of soil from many different areas in your lawn, and collect the part of the slice that is roughly 4-6" deep.

2) Mix the samples together in a bucket, and then fill the sample container to the level requested. Your soil texture and chemistry will vary quite a bit from one spot to another, so you're trying to get an average profile.

3) Mail the sample off to the state lab, or take it to the Extension office if so instructed, along with your fee.

You will receive a printed report from the lab that will look something like this. (Click on the photo to expand it.)

2010-09-06/knoxred/d6770a

Note that of the 3 major soil nutrients Nitrogen (N), Phosporus(P) and Potassium (K), only P and K are measured.  Nitrogen levels change quite rapidly in the soil, and are generally not included in a regular soil test.  Minor nutrients such as calcium, magnesium, zinc, and manganese are also included because they are critical nutrients for certain specific crops. Agriculture in your state relies on such soil test reports for growing both edible and ornamental crops.

Finally, and probably the most interesting to you, is the soil pH level.  An acidic (low) pH can be adjusted or "sweetened" with limestone, and an alkaline (high) pH can be brought down with applications of sulfur. 

The report will guide you in the type and quantities of amendments you need to add to your soil, and may also include some general growing and maintenance tips.  If you need help in interpreting the test report, your Extension agent can help.

A side note: the recommendations in this report call for fertilizer applications of ammonium nitrate, because the pH in this example already is low and fertilizers such as ammonium sulfate will tend to lower the pH even further.  However, unless you are a legitimate big-time farmer on good terms with Homeland Security, you may have trouble getting ammonium nitrate.  After appearing in the news too many times for, shall we say, non-agricultural reasons, it has been replaced on most store shelves with less, um "explosive" choices.  If you can't find the exact product recommended, read labels, and do your homework to get a product that is appropriate for your situation. 

Related articles:
acid, acidic, acidity, alkaline, ammonium, ammonium nitrate, base, calci, extension, level, limestone, magnesium, major, manganese, minor, nitrogen, nutrients, pH, phosphorus, potassium, sample, sampling, soil, sulfate, sulfur, sweeten, test, testing

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Comments and discussion:
Subject Thread Starter Last Reply Replies
Great article gardenersdetective Sep 22, 2010 7:15 AM 3

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"The most serious gardening I do would seem very strange to an onlooker, for it involves hours of walking round in circles,
apparently doing nothing. What I'm doing is forcing myself to evaluate certain areas....
Only during these quiet moments does a good idea suddenly occur."
~ Helen Dillon, Irish garden writer